Ram Pressure Stripping of Disk Galaxies

Elke Schumacher, Institute of Theoretical Physics und Astrophysics Uni KielGerhard Hensler, Institute for Astronomy Uni Vienna

Environments of Galaxies, Crete, August 2004

Roediger

Analytical Estimate:

Analytical Estimate:

d/dz gas

(r) = fgrav

= p

ram =

ICMv

ICM

2

Analytical Estimate:

d/dz gas

(r) = fgrav

= p

ram =

ICMv

ICM

2

Analytical Estimate:

d/dz gas

(r) = fgrav

= p

ram =

ICMv

ICM <

> 2

Analytical Estimate:

d/dz gas

(r) = fgrav

= p

ram =

ICMv

ICM <

>

independent of Mach number?

independent ofvertical structure(thickness) ?

2

Analytical Estimate:

Scanning the wind parameter space:

cluster centres

to

outskirts

ICM sound speed ( TICM

=4107K)

The model galaxy: stellar disk mass 8 1010 Msun

bulge 2 1010 Msun

gas disk mass 8 109 Msun

DM mass (R<50kpc) 3.8 1011 Msun

The model galaxy gas disk:

10-3 cm-3=10-27 g cm-3

density:

The model galaxy gas disk:

same (r)

Results - time evolution:

10-3 cm-3=10-27 g cm-3

density:

nICM

vICM

=1000 cm -3 km2 / s22

Results - mass and radius of remaining disk:

measured:

a) mass inside disk region

b) bound mass

Results - mass and radius of remaining disk:

Results - mass and radius of remaining disk:

nICM

vICM

=1000 cm -3 km2 / s22

Results - mass and radius of remaining disk:

nICM

vICM

=1000 cm -3 km2 / s22

1Msun / yr

Results - mass and radius of remaining disk:

nICM

vICM

=10 000 cm -3 km2 / s22

Results - mass and radius of remaining disk:

nICM

vICM

=100 cm -3 km2 / s22

nICM

vICM

=10 cm -3 km2 / s2

Results - time evolution:2

Results - influence of vertical structure:

nICM

vICM

=1000 cm -3 km2 / s22

nICM

vICM

=1000 cm -3 km2 / s22

Results - influence of Mach number:

Comparison analytical-numerical:

nICM

vICM

=1000 cm -3 km2 / s22

Comparison analytical numerical

d/dz gas

(r) = fgrav

=

pram

= ICM

vICM

<>

2

Comparison analytical numerical

d/dz gas

(r) = fgrav

=

pram

= ICM

vICM

<>

2

Comparison analytical numerical

d/dz gas

(r) = fgrav

=

pram

= ICM

vICM

= 0.25

<>

2

How much gas does fall back?

•10 to 15% of original gas disk mass

ISM that has left the disk:

Conclusions:•Stripping radius can be predicted approximately by simple analytical estimate

•mainly dependent on ram pressure, slightly on Mach number

•independent of vertical structure of gas disk

•Cluster centres: heavy truncation and mass loss

- displacement of all but inner part in few 10Myr

- displaced gas unbound in few 100Myr

•Cluster outskirts: nearly no mass loss, yet truncation

- displacement of edge in few 100Myr

- displaced gas not gas unbound, but falls back

Future Work

•basis for further investigations:

- inhomogeneous ISM

- inclination (other than face-on)

- time-dependent wind cluster crossing

Timescales:

10x

Results - mass and radius of remaining disk:

nICM

vICM

=10 cm -3 km2 / s22

Results - location of bound gas:

nICM

vICM

=1000 cm -3 km2 / s22